The commercial use of coaxial vapor recovery hoses for the transfer of volatile fluids has been in existence for approximately a decade. These systems generally include a pair of hoses, one carrying fuel from a supply tank to a receiving tank, the other carrying fuel vapor from the receiving tank back to the supply tank. These systems generally provide for a relatively closed system to avoid the discharge of volatile vapors into the atmosphere.
Some prior art coaxial vapor recovery hose assemblies generally taught the use of a smaller diameter internal hose or conduit capable of withstanding surge pressures of 30 to 40 psig to deliver the volatile liquid such as gasoline from the supply tank to the receiving tank. The outer hose was taught to require a working pressure on the order of 120 psig. This capability of the outer hose was because of the construction which was required to withstand the severe abuse normally encountered in a gasoline service station as well as to protect the internal hose. These prior art outer hoses were also constructed so as to function as the tensile bearing member of the assembly. As a result of such constructions, the assemblies which have found their way into commerce, while being somewhat flexible are still relatively rigid necessitating the use of additional fittings such as swivel couplings between the nozzle assembly and the hose assemblies. In addition, the construction of the outer hose adds considerably to the weight of the assembly.